Scepticism in philosophical terms says that we cannot have complete certainty in human knowledge and so should refrain from claiming to make statements of truth. In more general terms, scepticism has become synonymous with a questioning attitude and a refusal to accept that which is presented to us as fact.
The Greek philosopher Pyrrho of Elis (360–270 BCE) is often identified as the original sceptic. Struggling to distinguish the ‘truth’ from the many versions proffered by disparate philosophical schools, he came to his inner peace by accepting that this was because none of them had logically proven their version as correct. Pyrrho thus became associated with the rejection of received wisdom and dogma, but his position was not merely negative. The Sceptic school that he founded remained committed to searching for truth that could be justified on a rational basis.
Pyrrho followed in a tradition arguably founded by Socrates, whose method of intellectual enquiry demanded the questioning of those who claimed knowledge.
The five major grounds for doubt
In the 1st century CE, Agrippa the Sceptic established the five major grounds for doubt:
• Dissent – uncertainty as shown by differences of opinion.
• Progress ad infinitum – proofs rooted in statements themselves in need of proof, and so on and on.
• Relation – an apparent proof may change as its relations change or it is viewed from a different perspective.
• Assumption – a statement of truth based on unsupported assumptions.
• Circularity – a statement of truth involving circular reasoning, so that the proof is dependent on the original statement.
By the 17th and 18th centuries, many of the Enlightenment’s leading figures – for example, France’s René Descartes and Blaise Pascal, England’s Francis Bacon and Scotland’s David Hume – started off from a position of scepticism. Indeed, the single best-known statement of the age, Descartes’ assertion that ‘I think, therefore I am’, is an implicit rejection of all other knowledge. In fact, the French literary critic Antoine Léonard Thomas famously revised Descartes’ words to ‘I doubt, therefore I think, therefore I am.’ Scepticism is today regarded as a necessary and admirable attribute for anyone undertaking serious intellectual investigation.